/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup spinfo
 */

#include <math.h>
#include <string.h>
#include <sys/stat.h>
#include <limits.h>
#include <assert.h>

#include "MEM_guardedalloc.h"

#include "BLF_api.h"

#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_string_utf8.h"

#include "GPU_immediate.h"
#include "GPU_state.h"

#include "BKE_text.h"

#include "textview.h"

static void console_font_begin(const int font_id, const int lheight)
{
  /* 0.875 is based on: 16 pixels lines get 14 pixel text */
  BLF_size(font_id, 0.875 * lheight, 72);
}

typedef struct ConsoleDrawContext {
  int font_id;
  int cwidth;
  int lheight;
  /** text vertical offset */
  int lofs;
  /** number of characters that fit into the width of the console (fixed width) */
  int console_width;
  int winx;
  int ymin, ymax;
  int *xy;   // [2]
  int *sel;  // [2]
  /* bottom of view == 0, top of file == combine chars, end of line is lower then start. */
  int *pos_pick;
  const int *mval;  // [2]
  int draw;
} ConsoleDrawContext;

BLI_INLINE void console_step_sel(ConsoleDrawContext *cdc, const int step)
{
  cdc->sel[0] += step;
  cdc->sel[1] += step;
}

static void console_draw_sel(const char *str,
                             const int sel[2],
                             const int xy[2],
                             const int str_len_draw,
                             int cwidth,
                             int lheight,
                             const unsigned char bg_sel[4])
{
  if (sel[0] <= str_len_draw && sel[1] >= 0) {
    const int sta = txt_utf8_offset_to_column(str, max_ii(sel[0], 0));
    const int end = txt_utf8_offset_to_column(str, min_ii(sel[1], str_len_draw));

    GPU_blend(true);
    GPU_blend_set_func_separate(
        GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);

    GPUVertFormat *format = immVertexFormat();
    uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_I32, 2, GPU_FETCH_INT_TO_FLOAT);
    immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

    immUniformColor4ubv(bg_sel);
    immRecti(pos, xy[0] + (cwidth * sta), xy[1] - 2 + lheight, xy[0] + (cwidth * end), xy[1] - 2);

    immUnbindProgram();

    GPU_blend(false);
  }
}

/* warning: allocated memory for 'offsets' must be freed by caller */
static int console_wrap_offsets(const char *str, int len, int width, int *lines, int **offsets)
{
  int i, end; /* column */
  int j;      /* mem */

  *lines = 1;

  *offsets = MEM_callocN(
      sizeof(**offsets) *
          (len * BLI_UTF8_WIDTH_MAX / MAX2(1, width - (BLI_UTF8_WIDTH_MAX - 1)) + 1),
      "console_wrap_offsets");
  (*offsets)[0] = 0;

  for (i = 0, end = width, j = 0; j < len && str[j]; j += BLI_str_utf8_size_safe(str + j)) {
    int columns = BLI_str_utf8_char_width_safe(str + j);

    if (i + columns > end) {
      (*offsets)[*lines] = j;
      (*lines)++;

      end = i + width;
    }
    i += columns;
  }
  return j; /* return actual length */
}

/* return 0 if the last line is off the screen
 * should be able to use this for any string type */

static int console_draw_string(ConsoleDrawContext *cdc,
                               const char *str,
                               int str_len,
                               const unsigned char fg[3],
                               const unsigned char bg[3],
                               const unsigned char bg_sel[4])
{
  int tot_lines; /* total number of lines for wrapping */
  int *offsets;  /* offsets of line beginnings for wrapping */
  int y_next;

  str_len = console_wrap_offsets(str, str_len, cdc->console_width, &tot_lines, &offsets);
  y_next = cdc->xy[1] + cdc->lheight * tot_lines;

  /* just advance the height */
  if (cdc->draw == 0) {
    if (cdc->pos_pick && cdc->mval[1] != INT_MAX && cdc->xy[1] <= cdc->mval[1]) {
      if (y_next >= cdc->mval[1]) {
        int ofs = 0;

        /* wrap */
        if (tot_lines > 1) {
          int iofs = (int)((float)(y_next - cdc->mval[1]) / cdc->lheight);
          ofs += offsets[MIN2(iofs, tot_lines - 1)];
        }

        /* last part */
        ofs += txt_utf8_column_to_offset(str + ofs, (int)floor((float)cdc->mval[0] / cdc->cwidth));

        CLAMP(ofs, 0, str_len);
        *cdc->pos_pick += str_len - ofs;
      }
      else {
        *cdc->pos_pick += str_len + 1;
      }
    }

    cdc->xy[1] = y_next;
    MEM_freeN(offsets);
    return 1;
  }
  else if (y_next < cdc->ymin) {
    /* have not reached the drawable area so don't break */
    cdc->xy[1] = y_next;

    /* adjust selection even if not drawing */
    if (cdc->sel[0] != cdc->sel[1]) {
      console_step_sel(cdc, -(str_len + 1));
    }

    MEM_freeN(offsets);
    return 1;
  }

  if (tot_lines > 1) { /* wrap? */
    const int initial_offset = offsets[tot_lines - 1];
    size_t len = str_len - initial_offset;
    const char *s = str + initial_offset;
    int i;

    int sel_orig[2];
    copy_v2_v2_int(sel_orig, cdc->sel);

    /* invert and swap for wrapping */
    cdc->sel[0] = str_len - sel_orig[1];
    cdc->sel[1] = str_len - sel_orig[0];

    if (bg) {
      GPUVertFormat *format = immVertexFormat();
      uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_I32, 2, GPU_FETCH_INT_TO_FLOAT);
      immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

      immUniformColor3ubv(bg);
      immRecti(pos, 0, cdc->xy[1], cdc->winx, (cdc->xy[1] + (cdc->lheight * tot_lines)));

      immUnbindProgram();
    }

    /* last part needs no clipping */
    BLF_position(cdc->font_id, cdc->xy[0], cdc->lofs + cdc->xy[1], 0);
    BLF_color3ubv(cdc->font_id, fg);
    BLF_draw_mono(cdc->font_id, s, len, cdc->cwidth);

    if (cdc->sel[0] != cdc->sel[1]) {
      console_step_sel(cdc, -initial_offset);
      /* BLF_color3ub(cdc->font_id, 255, 0, 0); // debug */
      console_draw_sel(s, cdc->sel, cdc->xy, len, cdc->cwidth, cdc->lheight, bg_sel);
    }

    cdc->xy[1] += cdc->lheight;

    for (i = tot_lines - 1; i > 0; i--) {
      len = offsets[i] - offsets[i - 1];
      s = str + offsets[i - 1];

      BLF_position(cdc->font_id, cdc->xy[0], cdc->lofs + cdc->xy[1], 0);
      BLF_draw_mono(cdc->font_id, s, len, cdc->cwidth);

      if (cdc->sel[0] != cdc->sel[1]) {
        console_step_sel(cdc, len);
        /* BLF_color3ub(cdc->font_id, 0, 255, 0); // debug */
        console_draw_sel(s, cdc->sel, cdc->xy, len, cdc->cwidth, cdc->lheight, bg_sel);
      }

      cdc->xy[1] += cdc->lheight;

      /* check if were out of view bounds */
      if (cdc->xy[1] > cdc->ymax) {
        MEM_freeN(offsets);
        return 0;
      }
    }

    copy_v2_v2_int(cdc->sel, sel_orig);
    console_step_sel(cdc, -(str_len + 1));
  }
  else { /* simple, no wrap */

    if (bg) {
      GPUVertFormat *format = immVertexFormat();
      uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_I32, 2, GPU_FETCH_INT_TO_FLOAT);
      immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

      immUniformColor3ubv(bg);
      immRecti(pos, 0, cdc->xy[1], cdc->winx, cdc->xy[1] + cdc->lheight);

      immUnbindProgram();
    }

    BLF_color3ubv(cdc->font_id, fg);
    BLF_position(cdc->font_id, cdc->xy[0], cdc->lofs + cdc->xy[1], 0);
    BLF_draw_mono(cdc->font_id, str, str_len, cdc->cwidth);

    if (cdc->sel[0] != cdc->sel[1]) {
      int isel[2];

      isel[0] = str_len - cdc->sel[1];
      isel[1] = str_len - cdc->sel[0];

      /* BLF_color3ub(cdc->font_id, 255, 255, 0); // debug */
      console_draw_sel(str, isel, cdc->xy, str_len, cdc->cwidth, cdc->lheight, bg_sel);
      console_step_sel(cdc, -(str_len + 1));
    }

    cdc->xy[1] += cdc->lheight;

    if (cdc->xy[1] > cdc->ymax) {
      MEM_freeN(offsets);
      return 0;
    }
  }

  MEM_freeN(offsets);
  return 1;
}

#define CONSOLE_DRAW_MARGIN 4

int textview_draw(
    TextViewContext *tvc, const int draw, int mval[2], void **mouse_pick, int *pos_pick)
{
  ConsoleDrawContext cdc = {0};

  int x_orig = CONSOLE_DRAW_MARGIN, y_orig = CONSOLE_DRAW_MARGIN + tvc->lheight / 6;
  int xy[2], y_prev;
  int sel[2] = {-1, -1}; /* defaults disabled */
  unsigned char fg[3], bg[3];
  const int font_id = blf_mono_font;

  console_font_begin(font_id, tvc->lheight);

  xy[0] = x_orig;
  xy[1] = y_orig;

  if (mval[1] != INT_MAX) {
    mval[1] += (tvc->ymin + CONSOLE_DRAW_MARGIN);
  }

  if (pos_pick) {
    *pos_pick = 0;
  }

  /* constants for the sequencer context */
  cdc.font_id = font_id;
  cdc.cwidth = (int)BLF_fixed_width(font_id);
  assert(cdc.cwidth > 0);
  cdc.lheight = tvc->lheight;
  cdc.lofs = -BLF_descender(font_id);
  /* note, scroll bar must be already subtracted () */
  cdc.console_width = (tvc->winx - (CONSOLE_DRAW_MARGIN * 2)) / cdc.cwidth;
  /* avoid divide by zero on small windows */
  if (cdc.console_width < 1) {
    cdc.console_width = 1;
  }
  cdc.winx = tvc->winx - CONSOLE_DRAW_MARGIN;
  cdc.ymin = tvc->ymin;
  cdc.ymax = tvc->ymax;
  cdc.xy = xy;
  cdc.sel = sel;
  cdc.pos_pick = pos_pick;
  cdc.mval = mval;
  cdc.draw = draw;

  /* shouldnt be needed */
  tvc->cwidth = cdc.cwidth;
  tvc->console_width = cdc.console_width;
  tvc->iter_index = 0;

  if (tvc->sel_start != tvc->sel_end) {
    sel[0] = tvc->sel_start;
    sel[1] = tvc->sel_end;
  }

  if (tvc->begin(tvc)) {
    unsigned char bg_sel[4] = {0};

    if (draw && tvc->const_colors) {
      tvc->const_colors(tvc, bg_sel);
    }

    do {
      const char *ext_line;
      int ext_len;
      int color_flag = 0;

      y_prev = xy[1];

      if (draw) {
        color_flag = tvc->line_color(tvc, fg, bg);
      }

      tvc->line_get(tvc, &ext_line, &ext_len);

      if (!console_draw_string(&cdc,
                               ext_line,
                               ext_len,
                               (color_flag & TVC_LINE_FG) ? fg : NULL,
                               (color_flag & TVC_LINE_BG) ? bg : NULL,
                               bg_sel)) {
        /* when drawing, if we pass v2d->cur.ymax, then quit */
        if (draw) {
          break; /* past the y limits */
        }
      }

      if ((mval[1] != INT_MAX) && (mval[1] >= y_prev && mval[1] <= xy[1])) {
        *mouse_pick = (void *)tvc->iter;
        break;
      }

      tvc->iter_index++;

    } while (tvc->step(tvc));
  }

  tvc->end(tvc);

  xy[1] += tvc->lheight * 2;

  return xy[1] - y_orig;
}
